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  #1 (permalink)  
Old 06-28-2010, 07:11 PM
crookedview's Avatar  
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Default Knock sound when turning car off


Occasionally, when I turn my car off, there's a knocking sound, fast at first and then 'winds down' until it goes away (probably 2-3 seconds). It sounds, and feels, like the engine is off.

I looked at this thread: Engine Knock? but didn't really find anything concrete.

Seems like it's only been doing it the past couple months, which I've replaced the ABS/ESP control modules, throttle body, and added a CAI. None of these seem like they would be the cause of the problem. I've changed the oil, using 0w-40 (8 quarts) and the correct WIX filter, but aside from that I have no idea what could be going on as I've not heard this in any of my other cars.

I'll try to get a sound file to post today or tomorrow, but until then, any ideas?
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Old 06-28-2010, 07:22 PM
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Default Re: Knock sound when turning car off


...Winding down......sounds like the fan is hitting something.
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Old 06-28-2010, 07:54 PM
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Default Re: Knock sound when turning car off


And it probably is. I had to replace the upper coolant hose because the fan slowing rubbed a hole in the side and made the hose blow. Have someone turn the car on and off for you with you looking under the hood maybe?


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Old 06-28-2010, 08:03 PM
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Default Re: Knock sound when turning car off


Quote:
Originally Posted by ProjectMayhem
And it probably is. I had to replace the upper coolant hose because the fan slowing rubbed a hole in the side and made the hose blow. Have someone turn the car on and off for you with you looking under the hood maybe?
There is a recall or TSB on this.
Go to Chrysler.com > owners and enter your VIN to check if your car is part of the recall.

Last edited by 70GT6; 06-28-2010 at 08:14 PM.
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  #5 (permalink)  
Old 06-28-2010, 08:11 PM
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Default Re: Knock sound when turning car off


Quote:
Originally Posted by ProjectMayhem
And it probably is. I had to replace the upper coolant hose because the fan slowing rubbed a hole in the side and made the hose blow. Have someone turn the car on and off for you with you looking under the hood maybe?
Are you sure it was not the fan shroud that was rubbing the hose, as there is a TSB on that issue. It seemed to occur on 2004 models, mine among them, and the fix is to turn the hose a little, which moves it away from the shroud.
I really can't see the fan hitting the hose when the engine has stopped because it would be too obvious and the hose would not last too long.
I would think that if some object was in the heating fan area it may hit the fan there and that has certainly occurred before.



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Old 06-28-2010, 10:11 PM
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Default Re: Knock sound when turning car off


the only noise I hear when cutting mine off is a knocking sound from the lifters oiling down on shutoff


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  #7 (permalink)  
Old 06-29-2010, 10:18 PM
 
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Default Re: Knock sound when turning car off


do you have the six speed or the auto? because i have the same noise when turning the car off. i though it was the engine but when i push in the clutch and turn it off there is no knocking sound. maybe something in the transmission.
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Old 07-20-2010, 02:28 AM
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Default Re: Knock sound when turning car off


Quote:
Originally Posted by hines.eddie
do you have the six speed or the auto? because i have the same noise when turning the car off. i though it was the engine but when i push in the clutch and turn it off there is no knocking sound. maybe something in the transmission.
That is exactly what my car does??? I just posted it yesterday in the roadster sec. asking if anyone had a clue. No responses. im asking the dealer about it tomorrow.
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Old 07-20-2010, 02:53 AM
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Default Re: Knock sound when turning car off


6spd. Both make the same noise. The litters are hydraulic when they lose pressure on shut down they chatter


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Old 07-20-2010, 03:41 AM
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Default Re: Knock sound when turning car off


Quote:
Originally Posted by Infinite
6spd. Both make the same noise. The litters are hydraulic when they lose pressure on shut down they chatter
The litters?? Im not sure I know what that is? So I can assume that
all 6spds make this noise then? Thanks for the reply.
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Old 07-20-2010, 03:56 AM
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Default Re: Knock sound when turning car off


lifters, sorry I was on my phone. autospell hates me sometimes


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Old 07-20-2010, 05:06 AM
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Default Re: Knock sound when turning car off


Guys, it's always a good practice to let your car idle for 1 minute before shutting it off in your driveway....especially a turbo charged car. it allows the engine to circulate & cool down an engine especially after it's been driven hard.

Also a slight knocking clinging sound is normal upon shutting. As it's the exhaust system contracting after it's expansion during the heat up with the engine heat. It's a normal sound. Other knocking is not normal. Try a higher gasoline octane to limit engine knock & run-on after shut down.

Hope i helped a bit!
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Old 07-20-2010, 06:02 AM
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Default Re: Knock sound when turning car off


has nothing to do with it. this is a mechanical function of the engine, nothing more. nothing you can do about it unless you run an accumulator


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Old 07-21-2010, 12:36 AM
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Default Re: Knock sound when turning car off


Holy smokes, forgot I even started this thread :|

It ended up being my cooling fan. Seems that it was slightly off-balance and rubbing around the outer rim of the fan.

Easiest way to find out if it's the fan is to have someone else turn your car off after the fan has been running.
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Old 07-21-2010, 12:40 AM
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Default Re: Knock sound when turning car off


I get 2 ponits
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Old 07-21-2010, 01:34 AM
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Default Re: Knock sound when turning car off


my fan doesnt rub, my lifters are just noisy


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Old 07-21-2010, 02:24 AM
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Default Re: Knock sound when turning car off


Quote:
Originally Posted by antonio311
Guys, it's always a good practice to let your car idle for 1 minute before shutting it off in your driveway....especially a turbo charged car. it allows the engine to circulate & cool down an engine especially after it's been driven hard.

Also a slight knocking clinging sound is normal upon shutting. As it's the exhaust system contracting after it's expansion during the heat up with the engine heat. It's a normal sound. Other knocking is not normal. Try a higher gasoline octane to limit engine knock & run-on after shut down.

Hope i helped a bit!
Thanks for the reply. My car is not a turbo and I understand what you are saying about the ticking of the cooling exhaust on shutdown. My issue is not those. I usually do let it idle a min. or so before shutdown. I am wondering why the clunk with the clutch pedal not pressed and no clunk when it is pressed in on shutdown. I have heard of thers with this issue I wonder if it is all 6 spds and is normal? I only run 93 octane. It dosen't sound good. Thanks.

Last edited by SillyMan; 07-21-2010 at 02:28 AM.
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  #18 (permalink)  
Old 07-21-2010, 02:26 AM
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Default Re: Knock sound when turning car off


Quote:
Originally Posted by Infinite
lifters, sorry I was on my phone. autospell hates me sometimes
No problem Infinite. How would that not happen when the clutch is pressed in if it's the lifters? also please see my other post for more info on this. Thanks!
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  #19 (permalink)  
Old 09-14-2010, 05:06 AM
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Default Re: Knock sound when turning car off


Most of the time the fan is just hitting something which cause the noise but the engine can be at fault too. But it can be the fan, the coolant, or throttle body that cause the sound. Better check all the car parts to be sure.
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Old 09-14-2010, 05:16 AM
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Default Re: Knock sound when turning car off


coolant doesnt make a knocking sound, nor does the throttle body.

The M112 motors have hydraulic lifters... When they lose oil pressure on shutdown they collapse, causing valvetrain chatter for the last few revolutions of the motor as it spins down. Thats what you are hearing. If it were the fan it would be a constant sound as the fan would be hitting that same point everytime it engaged.........................


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Old 09-14-2010, 05:16 AM
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